This invention relates generally to an electrical switch, and more particularly to a dimmer switch with a control circuit for automatically increasing or decreasing light intensity by either full scale or incremental amounts.
Dimmer switches are well known devices for saving electrical power to or varying the light intensity of an illuminating device usually between a fully on state and a fully off state. Such dimmer switches typically include a variable resistance which the user adjusts for varying the electrical power to the light source to alter the light source intensity. Dimmer switches typically include mechanical components which provide only coarse adjustments to the illuminating device and other loads. When the dimmer switch regulates electrical power to an illuminating device in a vehicle dashboard, for example, the addition of other accessories in the vehicle can typically increase the load of the dimmer switch circuit to a level that can lead to damage to the dimmer switch and surrounding components. Even inadvertent jostling of the dimmer switch can result in the light intensity of the load undesirably jumping to either a fully on state or a fully off state. An object of the present invention is to provide a dimmer switch control assembly that overcomes the drawbacks and disadvantages associated with prior dimmer switches.
In one aspect of the present invention a dimmer switch assembly includes a housing for supporting and enclosing the assembly components. A dimmer adjusting element is mounted on the housing and has a movable portion for movement in first and second directions. A triggering device is coupled to the movable portion of the dimmer adjusting element. First and second detectors, preferably microswitches, are spaced from one another. The triggering device is interposed between the detectors such that movement of the triggering device upon movement of the movable portion of the dimmer adjusting element in the first direction activates the first detector, and movement of the triggering device upon movement of the movable portion of the dimmer adjusting element in the second direction activates the second detector. The detectors generate input signals to a dimmer control circuit such that the dimmer control circuit provides a dimmer intensity output signal to decrease the intensity of a light source when the first detector is activated, and to increase the intensity of the light source when the second detector is activated.
In a first alternative embodiment the dimmer switch assembly includes a dimmer adjusting element mounted on the housing and a movable portion thereof for movement in first and second directions. An elongated flexible triggering member has a first longitudinal end coupled to the movable portion of the dimmer adjusting element and a second longitudinal end provided in a socket fixed in the housing. First and second detectors are spaced from and arranged opposite to one another. The elongated member is interposed between the detectors such that movement of the dimmer adjusting element in the first direction flexes the elongated member toward to activate the first detector, and movement of the dimmer adjusting element in the second direction flexes the elongated member toward to activate the second detector. The detectors have signals associated respectively therewith which are generated by the detectors when the detectors are activated by the triggering device. A dimmer control circuit has as inputs the signals from the first and the second detectors for adjusting a dimmer intensity output signal to decrease the intensity of a light source when the first detector is activated, and to increase the intensity of the light source when the second detector is activated.
In a second alternative embodiment the dimmer switch assembly includes a dimmer adjusting element mounted on the housing so that a movable portion moves in first and second directions. First and second detectors are spaced from one another within the housing. A triggering device has a first end coupled to the movable portion of the dimmer adjusting element and a second end. The triggering device further includes a butterfly-shaped member pivotally coupled to the housing. The second end of the triggering device is movable with the movable portion of the dimmer adjusting element in the first direction for engaging and pivoting a first wing of the butterfly-shaped member toward to thereupon activate the first detector, and the second end of the triggering device is movable with the movable portion of the dimmer adjusting element in the second direction for engaging and pivoting a second wing of the butterfly-shaped member toward to thereupon activate the second detector. A dimmer control circuit has as inputs the signals from the first and the second detectors for adjusting a dimmer intensity output signal to decrease the intensity of a light source when the first detector is activated, and to increase the intensity of the light source when the second detector is activated.
Preferably the control circuit includes a controller that employs pulse width modulation to adjust electrical power supplied to the load. The controller is also preferably programmable to select minimum, maximum and rate of change settings of the duty cycle of the pulse width modulation signal. The control circuit preferably also includes a temperature sensor to lower the electrical power to the load should the surrounding temperature reach a maximum threshold.
An advantage of the present invention when powering an illuminating device is that inadvertent bumping of the dimmer switch assembly will not change the switch intensity to one extreme or the other, but will only change the intensity a small discrete amount.
Another advantage of the present invention is that the programmable controller using pulse width modulation provides flexible and precise adjustments to be made to the light intensity of the load through the dimmer switch assembly.
Another advantage of the present invention is that the temperature sensor will lower the electrical load to a predetermined value when the surrounding temperature reaches a threshold value in order to prevent damage to the dimmer switch assembly and other adjacent components. This feature is particularly useful when the dimmer switch is set up to operate an illuminating device in a vehicle dashboard because the addition of after market accessories can increase the load beyond the design intent.
These and other advantages of the present invention will become more apparent in the light of the following detailed description and accompanying figures.